Corporate top executives' adaptation to big data technological trends and timely updating of traditional mindsets play crucial roles in driv-ing corporate innovation.Grounded in the expansion logic of big data technology and upper echelons theory,this study investigates how executives' big data thinking influences corporate innovation.By utilizing machine learning methods,we construct a big data thinking indicator for corporate executives and find that such thinking significantly enhances corporate innovation levels.Mechanism analysis reveals that big data thinking improves organizational capa-bilities in handling complex information environments,with more pronounced innovation-enhancing effects observed when firms face a more complex infor-mation environment or when management teams lack science and engineering educational backgrounds.Further analysis demonstrates that executives' big data thinking effectively improves innovation quality.This research extends the investigation into the economic consequences of big data development from a cognitive perspective,provides empirical evidence for stimulating corporate innovation vitality,and offers policy implications for promoting high-quality e-conomic development.

根据新时代人才培养的新要求,结合普通高等院校工程力学专业弹性力学课程的特点,从教学内容优化、加强理论联系实际(工程案例)、引入课程思政、课程全过程考核等方面出发,开展课程教学研究与实践,持续改进教学效果,提高人才培养质量.

The elastic analysis of anisotropic rotating sandwich ring with a functionally graded transition region was carried out. Like the shell sandwich structure in nature, the ring is composed of 3 well-bonded regions, of which the inner and outer regions are made of homogeneous anisotropic materials, and the intermediate transition region is made of a material with arbitrary-gradient properties along the radial direction. Based on the boundary conditions and the continuity conditions at the interface, the 2nd Fredholm integral equation for the radial stress was obtained with the integral equation method, then the stress and displacement fields of the sandwich ring structure were obtained through numerical solution. The distributions of the stress and displacement fields in the sandwich ring structure were given. Different gradient changes encountered in engineering practice can be solved only through substitution of the corresponding function model. The effectiveness and accuracy of the integral equation method were verified through comparison of the numerical solutions with the exact ones for a special power function gradient variation form. The more general Voigt function model was adopted for the intermediate transition region, and the influences of the anisotropy degree, the gradient parameter, and the thickness on the stress and displacement fields were analyzed. The proposed Fredholm integral equation method provides a powerful tool for the optimal design of anisotropic functionally graded materials and sandwich ring structures. The numerical results make a theoretical guidance for the safety design of anisotropic functionally graded sandwich ring structures.

创新型基础力学人才的培养既要注重专业知识的学习,又要重视学生思辨、质疑与应用能力的提升.受限于不断削减的学时,传统基础力学课程仍以讲授为主,难以开展有效的实践教学环节.这种重理论轻实践的模式易导致学生学习兴趣下降、综合能力不足.为弥补实践短板,国内高校正逐步开展各类型大学生实践项目.本文以大学生创新训练项目为例,系统介绍项目实施期间教师有效的引导方式,以期为新时期力学人才培养贡献力量.

This study investigates a special firm-media connection, whether and how media experts sit on the independent board affects the firm's stock pricing efficiency. Using stock price synchronicity as measurement, we find that independent directors with media experience significantly reduce stock price synchronicity, especially when firms with server information asymmetry, or directors from influential media outlets. We provide evidence that the effect is driven by media-linked directors' information dissemination role rather than sentimental trading noise, as media-connected firms provide more firm-specific information and receive more media coverage. Furthermore, firm-media connections have a positive impact on firm value and help manage negative industry shocks. Overall, our evidence sheds light on understanding the information role of media experts sitting on the board.

地铁施工过程中的振动对地表结构的影响已成为不可忽视的问题.文中利用振动波能量扩散关系替代有限土体结构的振型分布,通过叠加有限土体的频率响应特性得到地下到地表的振动传递关系,分析土体垂直方向振动衰减率,评估地铁施工振动效应.

本文考察了会计信息可比性对公司违规行为的影响,以2007～2018年上市公司数据为样本研究发现,提高会计信息可比性能够降低公司违规倾向,提升公司违规被查处的概率,从而降低公司违规行为.较之国有企业,会计信息可比性在民营企业中的治理效应更为显著.较之于分析师关注度较高的公司,会计信息可比性在分析师关注度较低公司的治理效应更为显著.进一步研究表明,会计信息可比性通过降低信息不对称程度产生中介作用.

为研究车轮横向分布对钢桥面板顶板-U肋连接处疲劳损伤的影响,以佛山平胜大桥为研究对象,通过数值模拟,计算各车型车轮荷载不同横向位置下顶板-U肋连接处的应力,采用英国规范BS5400计算该处的疲劳损伤度;建立车轮分布模型,计算车轮在车道不同位置的分布概率,提出考虑车轮横向分布的疲劳损伤计算方法.结果表明,顶板-U肋连接处的应力幅受车轮横向分布的影响范围较小,约为1.5 m,不必考虑多车效应;U肋损伤分布差异较大,U肋底板损伤比腹板损伤更严重;考虑车轮横向分布效应后,顶板-U肋连接处的疲劳寿命计算值提高69％,钢桥面板疲劳损伤分析中应考虑车轮的横向分布效应.

依据已有支管受轴向荷载的T型焊接圆管节点的实验数据,使用ANSYS进行了有限元分析,并利用临界距离理论的点法和线法,预测了构件的疲劳强度.选取第一主应力点沿其最大梯度方向作为临界距离理论的聚焦路径.研究结果表明:预测的疲劳强度与疲劳强度实测值的误差在20％以内.临界距离理论能够在实验数据不足的情况下对焊接管节点的疲劳性能提供较精确的理论预测,为工程应用提供有价值的参考.

为了研究TB5钛合金板试件从微观初始缺陷到宏观疲劳断裂全过程中的跨尺度数值模拟问题,以约束应力表征材料的疲劳损伤度,以约束应力区裂纹模型描述材料从微观到宏观的疲劳破坏过程,以应变能密度因子作为宏微观跨尺度疲劳裂纹扩张的控制参量,发展了一种宏微观跨尺度疲劳破坏过程的数值模拟方法.在该模型中,可通过疲劳源处材料初始缺陷大小和3个尺度效应函数来表征材料微观因素对疲劳破坏过程的影响.对TB5钛合金光滑板试件(应力集中系数K t=1)和含切口板试件(K t=3)进行了数值模拟计算,结果表明,计算S-N曲线与试验S-N曲线能够精准吻合.通过考虑微观效应,其疲劳寿命试验数据的离散性也可由模型计算结果得以体现.

A new three-dimensional trans-scale crack growth model, developed from the microscale to macroscale, is presented based on the concept of restraining stress zone. It aims to simulate the growth behaviors of fatigue cracks in a welded joint of orthotropic steel decks. In the study, the crack shape was first simplified as a semielliptical surface crack, and analyzed in a finite-element mode considering the trans-scale stress intensity factors (SIFs). Subsequently, the trans-scale SIFs served as controlling parameters for the propagation of fatigue crack from the microscale to macroscale. The proposed model can simulate the overall process of fatigue failure of orthotropic steel deck details. Comparison between numerical simulations and results from the experimental S-N curves given in the literature provides two conclusions: (1)the three-dimensional trans-scale crack growth model accurately depicts the trans-scale behaviors of fatigue failure of the weld joint between the longitudinal ribs and deck plate of the orthotropic steel deck; and (2)the model well explained the scatter phenomenon of the fatigue test data due to the microscopic effects. In addition, the initial microdefects have a significant influence on the fatigue life, and the microscopic effects in a fatigue process can be considered by the proposed model.

A damage constitutive model with 3 independent parameters is derived from the two-order form of the general theory for elastic damage problems. Based on this damage constitutive model and by using damage mechanics – additional load – finite element method, a three dimensional finite element analysis computer program is established. The damaging process and failure of a reinforced concrete arch structure which was removed from a real old bridge is simulated numerically. The damage parameters of concrete are determined through a targeting calculation process. The values of element damage and the nodal displacements along three directions under different load level are obtained. The theoretical results of the failure mode, displacements are in good agreement with the experimental observations. Numerical results reveal the complicated behavior of concrete in a damaging process. The reinforced concrete structures exhibit pronounced nonlinearity at large loading levels.

A trans-scale model of 3D semi-ellipse surface crack based on the restraining stress zone was developed for accurately simulate the fatigue crack propagation behavior of orthotropic steel bridge deck.The finite element method was applied to calculate the stress intensity factor.The trans-scale stress intensity factor was used as controlling parameter for the fatigue crack growth from micro-scale to macro-scale.Therefore,the whole fatigue failure process could be described by a unified model.Numerical simulation was performed for the fatigue failure behavior of an orthotropic steel bridge deck.Comparison and analysis were made between the theoretical results and experimental S-N curves.Results indicate that the trans-scale fatigue crack growth model can correctly describe the fatigue failure process of the welded joint between bridge deck and U-rib of orthotropic steel bridge decks.As is known that the microscopic effects have great influence on the fatigue life;when the microscopic effects are taken into account,the scatter of the fatigue test data can be explained by the proposed multi-scale model.

运用ANSYS12.0建立5个不同抗剪连接程度钢-砼连续组合梁有限元非线性分析模型,分析正、负弯矩区不同抗剪连接程度对组合梁极限承载力、挠度、界面滑移及开裂荷载的影响.结果表明,抗剪连接程度对钢-混组合梁的滑移及变形均有一定程度的影响,其中负弯矩区抗剪连接程度对钢-砼组合梁承载性能的影响较大.

The strain gradient exists near a crack tip may significantly influence the near-tip stress field. In this paper, the strain gradient and the internal length scales are introduced into the basic equations of mode III crack by the modified gradient elasticity (MGE). By using a complex function approach, the analytical solution of stress fields for mode III crack problem is derived within MGE. When the internal length scales vanish, the stress fields can be simplified to the stress fields of classical linear elastic fracture mechanics. The results show that the singularity of the shear stress is made up of two parts, r(-1/2) part and r(-3/2) part, and the sign of the stress sigma(yz) changes. With the increase of l(X), the peak value of cryz decrease and its location moves farther from the fracture vertex. The influence of strain gradient for mode III crack problem cannot be ignored. (C) 2017 Elsevier Ltd. All rights reserved.

慕课是基于"互联网+"的一种新型教学方式.本文介绍了结构力学慕课的制作过程、慕课教学的实施,及教学效果的分析.实践表明,慕课教学具有灵活、主动、分享、即时互动等优点,取得了令人满意的教学效果.

为了研究微观因素对铸铁材料极限强度的影响,根据材料的破坏机理,提出了一种宏、微观跨尺度裂纹扩展模型,该模型可描述材料从微观缺陷到宏观断裂的过程.模型中初始微观缺陷大小及3个尺度效应函数,代表着微观因素对破坏过程的影响.进行了铸铁试件的单向拉伸试验,根据试验数据,采用打靶计算,拟合出了模型中的2个材料特性参数.对铸铁试件的拉伸极限强度进行了计算,计算结果与铸铁件拉伸极限强度的试验数据完全吻合.研究结果表明,极限强度值受微观因素影响具有一定的离散性,可由模型得到正确反映.最后通过数值模拟计算,探讨了微观因素对材料破坏过程的影响.

用约束应力区描述材料损伤状态,建立耦合宏微观效应的跨尺度疲劳裂纹模型,可描述材料疲劳破坏从微观缺陷到宏观断裂的整个过程.约束应力的分布取决于材料的损伤状态.假定约束应力为线性分布,在远场均匀拉应力作用下,应用Muskhelishivili方法,对跨尺度裂纹模型进行了解析求解,得到了裂纹张开位移与跨尺度应变能密度因子的解析解.以跨尺度应变能密度因子作为疲劳裂纹从微观到宏观扩展的控制参量,对疲劳破坏全过程进行了数值模拟计算.以LC4铝合金板为例,利用模型精确再现出不同疲劳荷载作用下的实验S-N曲线.由于模型考虑了微观因素的影响,疲劳实验数据的发散特性也精确再现出来.另外,通过数值计算,分析了微观效应对疲劳裂纹扩展行为的影响.

Considering the surface irregularities of the bridge and nonlinear influence,ac-cording to D'Alembert's principle,the basic dynamic equations of vehicle-bridge interaction system are formulated.With the application of modal analysis method,the nonlinear dy-namic equations are deduced using generalized coordinates.By Runge-Kutta methods and Visual Fortran program,the displacement response curves of the beam bridge and the curves of impact effect are obtained.The nonlinear dynamic influence on beam bridges is calculated considering the change of system parameters.According to the results,the non-linear influence on beam bridges is changed with the change of parameters,including span, flexural stiffness,velocity of vehicle and surface roughness.

采用界面单剪试验考察了FRP-混凝土界面的粘结行为.基于试验结果和不可逆热力学的弹性损伤理论建立了有限元模型,模拟了FRP-混凝土界面在加载过程中的损伤演化,提出了混凝土材料的损伤本构模型,编制了相应的ABAQUS用户子程序.结果表明,FRP-混凝土试件的数值计算结果与试验结果吻合较好,验证了有限元模型的正确性,并给出了混凝土本构模型中损伤特性参数的取值.研究结果表明,提出的基于损伤理论的有限元数值计算方法能够很好地描述FRP-混凝土构件整个界面的损伤演化和剥离破坏过程.